Are AB and ST Magnitude Systems Interchangeable?

In summary, the AB and ST magnitude systems are two different ways of measuring the brightness of objects in the night sky. The AB system is based on a logarithmic scale, while the ST system is based on a linear scale. The AB system is more commonly used in modern astronomy due to its accuracy and ability to be applied to a wider range of objects. The two systems can be converted to each other using a simple formula, but the conversion is only valid for objects emitting light at a single wavelength. The use of different magnitude systems can affect our understanding of the universe and there are many other magnitude systems used in astronomy, each with its own reference point and scale.
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Are the ST and AB magnitude systems equivalent? In other words, should they give the same value for a particular luminosity per unit wavelength? If not, is there an explicit conversion between the two?
 
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No, the ST and AB magnitude systems are not equivalent. They are two different ways of measuring a star's brightness, and their values for a particular luminosity per unit wavelength will differ. There is no explicit conversion between the two systems, as the difference in magnitude between the two scales depends on the spectral type of the star being measured.
 

1. What is the difference between AB and ST magnitude systems?

The AB and ST magnitude systems are two different ways of measuring the brightness of astronomical objects. The AB system is based on the energy received from the object, while the ST system is based on the number of photons received from the object.

2. Which magnitude system is more commonly used?

The AB magnitude system is more commonly used in modern astronomy. It is the standard system used by most telescopes and is considered to be more accurate and consistent.

3. How do the two systems differ in terms of zero point?

The zero point of the AB system is defined by a hypothetical object with a specific energy flux, while the zero point of the ST system is defined by a specific number of photons received. This means that the zero points of the two systems are not equivalent.

4. Can the two systems be converted into each other?

Yes, it is possible to convert magnitudes from the AB system to the ST system and vice versa. However, this conversion is not a simple mathematical formula and requires knowledge of the spectral energy distribution of the object being measured.

5. Which magnitude system is more suitable for measuring different types of objects?

The AB system is more suitable for measuring objects with a broad range of spectral energy distributions, such as galaxies and quasars. The ST system is more suitable for measuring objects with a specific spectral energy distribution, such as stars.

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